1. Field of the Invention
The present invention relates to a multi-band radio terminal and a band switching method used therefor and a program thereof and, more particularly, a band switching method at a radio portable terminal adaptable to multi-band.
2. Description of the Related Art
In recent years, more and more multi-band-adaptable radio portable terminals have been produced. In Japan, dual-band terminals adapted to 800 MHz band (PDC: Personal Digital Cellular) and 1.9 GHz band (PHS: Personal Handyphone System) have been already put on the domestic market and other multi-band terminals having more varieties of frequency bands are expected to be produced hereafter.
Example of a structure of the above-described dual-band terminal is shown in FIG. 5. In FIG. 5, the dual-band terminal includes an antenna (ANT#1) 110 and a Band (#1) adaptation unit 150 adaptable to a band #1 as a first band, an antenna (ANT#2) 120 and a Band (#2) adaptation unit 160 adaptable to a band #2 as a second band, a band switching unit 170 and a host sequence 130.
The Band (#1) adaptation unit 150 includes a radio transmitter and receiver unit 151, a three wire serial signal generation unit 152, a register conversion unit 153, a frequency control unit 154 and frequency setting data 155.
The Band (#2) adaptation unit 160 includes a radio transmitter and receiver unit 161, a three wire serial signal generation unit 162, a register conversion unit 163, a frequency control unit 164 and frequency setting data 165.
The band switching unit 170 controls the radio transmitter and receiver units 151 and 161 and the frequency control units 154 and 164 in response to an instruction from the host sequence 130 to operate either the antenna (ANT#1) 110 and the Band (#1) adaptation unit 150 or the antenna (ANT#2) 120 and the Band (#2) adaptation unit 160, thereby switching a band (see Japanese Patent Laying-Open (Kokai) No. Heisei 11-251951, for example).
In the above-described conventional dual-band terminal, since all control for band switching and setting of a frequency is performed by a control unit (CPU: central processing unit), operation of a control unit (CPU) becomes very complicated.